Final answer:
The Supreme Court outlawed bus segregation on December 21, 1956, following the Montgomery Bus Boycott, which allowed African Americans to sit wherever they wished on public buses. Earlier, in 1946, the Morgan v. Commonwealth of Virginia decision ruled that interstate bus segregation was unconstitutional.
Step-by-step explanation:
The Supreme Court and Desegregation of Buses
The Supreme Court made several rulings regarding segregation that directly affected bus seating in the United States. The most significant came after the events of the Montgomery Bus Boycott. In response to a lawsuit filed by the boycotters, the Supreme Court decision in November 1956, which came into effect on December 21, 1956, declared bus segregation unconstitutional. This landmark decision allowed African Americans to sit wherever they wanted on public buses.
Earlier, in 1946, the Supreme Court ruled in Morgan v. Commonwealth of Virginia that segregation on interstate buses was unconstitutional. However, it did not effectively end the separate but equal policy in all intrastate transportation. This decision was further reinforced by the subsequent actions of the Freedom Riders in 1961, who rode in an integrated manner to challenge the enforcement of desegregation laws on interstate transportation following the Supreme Court decision.